MEXICO CITY (Reuters) - Mexico’s presidential front-runner Andres Manuel Lopez Obrador denied any wrongdoing on Wednesday after another candidate accused him of improperly awarding government contracts to a construction mogul when he was Mexico City mayor.

Lopez Obrador told reporters on Wednesday the contracts given to Rioboo did not violate any law and studies showed he was the best man for the job.

“Andres Manuel (Lopez Obrador) you have turned into what you always criticized, just like the PRI (ruling political party) you also have your favorite contractors,” Anaya said during a tense moment at Tuesday night’s round table discussion.

“Yes or no? When you were mayor you directly granted contracts, with no bidding process for 170 million pesos?” Anaya asked.

Lopez Obrador shot back: “No, what you’re saying makes no sense. I’ll tell you no, no I am not corrupt ... I am not corrupt like you.”

Reuters reviewed the documents cited by Anaya. They show that a trust that managed roadway infrastructure in Mexico City during Lopez Obrador’s 2000-2005 tenure as mayor gave contracts directly to Rioboo to build an elevated highway around part of the city.

Lopez Obrador said the project was audited several times.

Rioboo’s firm did not respond to requests for comment.

Lopez Obrador has amassed a double-digit lead in most polls ahead of the July 1 vote and says his administration will root out corruption, which he estimates costs government coffers 500 billion Mexican pesos ($24 billion) annually.

In his third bid to reach the presidency, Lopez Obrador says if elected that money would be used to boost the economy, jobs and improve public safety.

He says he would scrutinize for signs of corruption in contracts granted by President Enrique Pena Nieto’s Institutional Revolutionary Party (PRI) for the development of the new massive Mexico City airport and exploration and production in the oil and gas sector.